Method of making pneumatic cushions



Feb. 10, 1942. c. BEAL 2,272,239

METHOD OF MAKING PNEUMATIC CUSHIONS I Fil'ed Dec. 10, 1936 Q W [EH/ 1555! Patented Feb, 10, 1942 v METHOD or MAKING minim CUSHIONS 1 Carl L. Beal, Cuyahoga Falls, Ohio, assignor to American Anode Inc., Akron, Ohio, a corporation of Delaware Application December 10, V1936, Serial No. 115,240

4 Claims. (01. 18-58) i This invention relatesto methods of making pneumatic cushions, matresses, and similar inflatable or distensible articles, and has for its principal object the provision of simple, economical and. efiicient procedure for manufacturing such articles by deposition of rubber substantially in final form directly'from a liquid dispersion of rubber, whereby the characteristic continuous rubber structure produced in such deposition processes may be embodied in the complicated structures of ventilated pneumatic cushions and the like with a complete elimination of seams and A reenforcements in the apertured cushioning zone of the article. The manner in which these and other objects of the invention are attained may be readily understood from the following detailed description of a preferred embodiment of I the invention as exemplified by the manufacture of an inflatable cushion for an aviator's parachute pack, which must be as light and compact as possible without sacrifice of cushioning qualities,

must be ventilated, i. e. must have several apertures to provide for free circulation of air about the cushion, and also must include a relatively largeopening to accommodate the straps which attach the cushion to the parachute pack. In the description of the invention, reference will be had to the accompanying drawing, of which Fig. 1 is a sectional elevation illustrating a step in the process of the present invention and showing an assembled deposition form immersed in a liquid dispersion of rubber; Y

Fig. 2 is a vertical section taken on line 22 of Fig. 1;

Fig. 3 is a vertical section taken on line 3-3 of Fi 1;

Fig. 4 is a perspective view illustrating a further step in the process and showing a portion of the deposition form being removed from a rubber deposit produced thereon;

Fig. 5 'is a sectional elevation illustrating a later step in the process;

Fig. 6 is an elevation showing the finished cushion made according to the present invention; and

that nooomplicated lockingmeans is required for holding the members in proper relation, the

tight-fitting dowel pins usually being adequatefor' that purpose. Auxiliary locking'means may be provided however, if desired. The mating edges of the form members II and I2, and I2 and I3, are provided with a plurality of oppositely disposed semi-elliptical edge indentations l1, Il

which mate in the assembled form I0 to provide two rows of generally elliptical apertures in the form. The mating edges of the form elements I3 and I4 are provided with longer and deeper indentations I8, I8 which mate in the asseml bled form to provide a rounded-end slot of substantial length designed to provide in the cushion to be produced thereon an opening of suitable size and length for accommodating the parachute pack straps.

In the process, the assembled form I0 is preferably immersed in aliquid dispersiorr of rubber 1 such as a suitably compounded concentrated natural rubber latex I9, and a depositof rubber 200i a desired thickness, for example, about 0.090 inch (when finished) is produced upon the form by any well known procedure, but preferably with aid of a coagulant preliminarily applied to the form toegther with a pulverulent separating material as described in U. S. PatentNo. 1,924,214, granted to Edwin B. Newton, August 29, 1933. In order that the desired tubular connecting links may be formed, the thickness of the rubber de-. posit 20 should never be sufliciently great to fill the apertures in the deposition form. As indicated above and more particularly in Fig. 7.0f

Fig. 7 is a vertical section taken on line 'I-'I of Fig. 6.

In manufacturing, for. example, an aviator's parachute pack cushion, I utilize a deposition form generally designated I0, comprising four complementary aluminum or other metal members II, I2, I3, and I4 designed to fit together in edge-to edge mating relation, guided by tightfitting dowel pins I5, to constitute the generally rectangular planar deposition form I0. The form I0 is provided with supporting pins I6, I6, removably threaded in the top edges of two of the members, preferably the outer two members II, and I4, for supporting the form with the individual form members in vertical positions so the drawing, the deposit 20 ordinarily will be relatively thin as compared with the extent of the apertures.

After the deposited rubber has been washed and dried according to conventional practice, the

supporting pins I6 are removedfrom the form l0,

and a slit ZI-is cut along the edge of the rubber deposit between the openings left by the pins. The rubber deposit is stretched enough to permit spreading the form members sufiiciently to free the dowel pins of one of the central form members, such as. the,member I2, and the free member is removed through the slit. Thereafter, the remaining form members are individually removed in a similar manner. As the tubular rubber connecting links produced. in the several apertures in the form prevent more than slight manipulation of the form members within the deposit, care must be exercised to avoid damaging of the rubber deposit by excessive stretching during removal of, especially, the two' outside' j members II and I4. To avoid such damage, it may be desirable in some cases partially to vulcanize the rubber before effecting removal of the form, but dried latex'rubber, even though unvulcanized, is quite tough and ordinarily will withously used, and depositing a coating of rubber about 0.045 inch thick (when finished) upon the immersed portion of the main rubber deposit 20 to produce a sealing deposit 22 capping the slit end of the main deposit. For symmetry of appearance, and also to provide reenforcement, a similar capping deposit of rubber 23 maybe produced upon the opposite edge of the main deposit as more clearly shown in Fig. 6. Finally a conventional valve 24 is inserted in a corner edge of the deposit, and the assembled article is vulcanized in any usual manner, as in a hot air oven, the article retaining its proper shape without the use of molds or the like by reason of the low temperature coeflicient of plasticity of unmasticated latex rubber deposited directly from liquid rubber latex.

The finished cushion illustrated in Fig. 6 is therefore seen to consist of a generally rectangu-,

lar hollow body 20 provided with. ventilating apertures 25, 25 and a strap-receiving aperture 26 extending through the body of the cushion. The walls throughout the cushioning zone including the apertures are of substantially uniform thickness and are entirely free of seams and seam-reenforcing strips which have been required in prior products with consequent undesirable stiffening of the structure and impairment of cushioning qualities as well as an undesirable increase in weight. The cushion embodies substantially throughout the characteristic tough, strong, continuous rubber structure produced only when rubber is deposited in final form directly from a liquid dispersion of rubber. The present invention accordingly provides a generally more satisfactory ventilated cushion of simple and durable construction, and provides procedure for manufacturing such pneumatic cushions in an economical and eflicient manner not possible in prior methods.

The term liquid dispersion of rubber" has been used in the specification and claims in a broad sense to include all flowable dispersions of rubber and analogous natural or synthetic materials in liquid vehicles; whether solvents or nonsolvents of rubber, and including artificially prepared aqueous dispersions, and solvent dispersions such as the so-called rubber cements as well as the natural rubber latex hereinabove specifically mentioned. All such dispersions may be compounded, uncompounded, vulcanized, unvulcanized, thickened, thinned, concentrated, diluted, stabilized, or otherwise prepared for use according to known procedures, and may contain any desirable added compounding or conditioning agents.

While the invention has been described in considerable detail with reference to certain preferred procedures, apparatus, and materials as applied to the manufacture of an aviator's cushion, it is obvious that numerous modifications and variations therein are possible and that the manufacture of other pneumatic articles including matresses, chair cushions, invalid cushions. and the like as well as other rubber articles designed for a variety of uses. All such modifications and variations are included within the spirit andscope of the invention as defined by the appended claims.

I claim:

1. A method of making a rubber article having opposed walls seamlessly connected by an integral tubular member, which comprises providing a deposition form comprising a pair of mating form members at least one of which is provided with an indentation in its mating edge surface, mounting the form members in matingrelation to provide a deposition form having an aperture therein defined by the said indentation, producing upon the assembled form an enveloping deposit of rubber, the rubber deposit being insufficient in thickness to fill the aperture, and removing the form members from within the rubber deposit.

2. A method of making a rubber article havin opposed walls seamlessly connected by an integral tubular member, which comprises providing a deposition form comprising a pair of mating form members each of which is provided with an indentation in its mating edge surface, mounting the form members with the said indentations in mating relation to provide a deposition form having an aperture therein defined by the mating indentations, producing upon the assembled form an enveloping deposit of rubber, the rubber deposit being insuflicient in thickness to fill the aperture, and removing the form members from within the rubber deposit.

3. A method of making a rubber article having opposed walls seamlessly connected by an integral tubular member, which comprises providing a deposition form comprising a pair of mating form members at least one of which is provided with an indentation in its mating edge surface, mounting the form members in mating relation to provide a deposition form having an aperture therein defined by the said indentation, producing upon the assembled form an enveloping deposit of rubber, the rubber deposit being insuilicient in thickness to fill the aperture, providing an opening in the rubber deposit, removing the form members through said opening, and thereafter sealing the opening.

4. The method of making an inflatable cushion or the like comprising a hollow rubber body havprinciples of the invention may be applied to the ing an integral tubular element seamlessly connecting opposed walls of the body and defining a transverse opening therethrough, which comprises providing a plurality of generally planar form elements adapted to be assembled in edgeto-edge mating relation, at least one of said elements having an indentation in its mating edge surface, mounting the form elements in mating relation to provide a generally planar deposition form having an aperture therein defined by the said indentation, associating a liquid dispersion of rubber with the assembled form to deposit thereon an enveloping coating of rubber, the coating of rubber bein insuflicient in thickness to fill the aperture, slitting the rubber coating along an edge thereof, individually removing the form elements through the slit, and thereafter sealing the slit by applying thereto a liquid dispersion of rubber and drying.

CARL L. BEAL. 

